London has been battered by 50mph winds that have felled trees and caused travel chaos. Powerful gusts swept across the capital as the Met Office issued a yellow "be aware" weather alert for most of the country.

A retired senior Scotland Yard police officer has admitted authorising secret recordings of a meeting between a friend of murdered teenager Stephen Lawrence, his lawyers and detectives.

Police officers had wanted "an unassailable record of what transpired" in meetings in 1999 and 2000, ex-deputy assistant commissioner John Grieve said.

Mr Grieve, who was director of the racial and violent crimes task force between 1998 and 2002, told the BBC he deeply regretted any distress, dismay or alarm that his decision may have caused Brooks, or Mr Lawrence's parents Doreen and Neville.

Mr Grieve said that at the time his team were both trying to solve Stephen Lawrence's murder and lead the Metropolitan Police response to charges of institutional racism after the Stephen Lawrence Inquiry report.

He denied that officers had sought to trick or deceive anyone involved in the meetings.

"Every member of our team was wholeheartedly committed to achieving long-overdue justice for Stephen, for his parents and for Duwayne Brooks as victims of a murderous, racist attack," he told the broadcaster.

"Every action taken was aimed at prosecuting and convicting Stephen's murderers.

"Every decision made was based on the information available at the time and conducted within ethical, legal, necessary and proportionate frameworks.

"This included taking all measures necessary to protect the integrity of witness evidence."

Mr Grieve added: "The organisations and individuals that make up the criminal justice system each have different roles, duties and needs; we may not have wanted to risk a situation where approval to record the meeting overtly was not given, potentially meaning that valuable evidence could have been lost."

The claims affecting Mr Brooks came after former undercover officer Peter Francis alleged that he had been told to find information to use to smear the Lawrence family.

Eighteen-year-old Stephen was waiting for a bus with Mr Brooks when he was murdered by racists in Eltham, south-east London, in 1993.

Mr Francis, who worked with Scotland Yard's former Special Demonstration Squad, spoke out about tactics that he said were used by the secretive unit in the 1980s and 1990s.

In the wake of his claims, Mr and Mrs Lawrence called for a public inquiry into the allegations, which the teenager's mother said made her feel "sick to the stomach".

Mr Grieve added: "Duwayne was both a victim and witness of the attack in 1993.

"It could be argued that failing to protect the integrity of any evidence that may have come to light at this meeting - and hence failing to protect Duwayne himself as a potential witness - would have been a neglect of duty.

"The relevance of this was subsequently borne out at the later successful trial where he was called as a witness."

The Metropolitan Police said that deputy assistant commissioner Fiona Taylor, who leads its Directorate of Professional Standards (DPS), wrote to Mr Brooks yesterday.

"This letter confirms that DPS investigators had found documentation authorising the recording of one meeting in May 2000 and that we continued to look for the recording which this authorisation related to.